The present invention relates generally to joining sheet metal or other sheet materials and more particularly to an apparatus for forming such joints and a method of forming such joints, as well as leakproof and non-leakproof joints formed thereby.
It is old in the art to join a plurality of pieces of sheet metal by punching or otherwise manipulating them to cause them to be deformed into an interlocking relationship in a localized area. However, insofar as Applicant is aware, such joints typically require the shearing of the sheet material and hence are not suitable for leakproof applications unless a sealant is applied. The formation of such joints is also frequently destructive of the corrosion resistance of coated materials. In addition, the known apparatuses for forming the joints are frequently relatively complex in design, often requiring powered actuation of both a punch and one or more portions of the die, and frequently require expensive sliding die portions. This complexity increases the cost of the equipment, as well as the energy required for operation.
It is therefore a primary object of the present invention to provide an improved method and apparatus for permanently joining sheet metal or other sheet material items, with the capability of forming either leakproof joints or conventional "lanced" joints. Additional objects reside in the provision of such a forming apparatus that is relatively simple but durable in construction, that can utilize standard or specialized punches, that requires very little power, that is compact and hence usable in many different applications, that substantially preserves the corrosion resistance of coated sheet materials being joined, and that is suited for use either as part of a small press or in C-frame holders in larger presses.
Another object of the present invention resides in the provision of an improved die assembly for use in sheet material joining apparatuses, and which is readily adapted to many different joint configurations, including conventional "lanced" joints as well as a novel leakproof joint.
Further objects of the present invention reside in the provision of a novel leakproof joint for sheet material as well as in the provision of a novel method for forming such a joint.
These and other objects, features and advantages of the present invention will become apparent from the subsequent description and the appended claims, taken in conjunction with the accompanying drawings.